Electrical accumulator cell or accumulator battery

ABSTRACT

Electric accumulator cell arranged in a cell box, the positive and negative essentially plane electrode plates being joined together into separate groups of electrodes by means of plate straps and being further lowered into a liquid electrolyte and provided with current discharging means for withdrawal of current to a consumer, said withdrawal taking place through at least two current discharging means connected to the corresponding number of plate straps on the electrode plates.

United States Patent Kuylenstierna 1 Oct. 2, 1973 ELECTRICAL ACCUMULATORCELL OR 1,665,772 4/l928 Carpenter 136/168 ACCUMULATOR BATTERY 2,505,2074/l950 Riggs 136/135 S [75] Inventor: John Fredrik Kuylenstierna,FOREIGN PATENTS OR APPLICATIONS oskarshamn, Swede" 241,014 10/1925 GreatBritain 136/134 R [73] Assignee: Svenska Ackumulator Aktiebolaget IJungner, Oskarshamn, Sweden Primary Examiner-Donald L. Walton A -S R th-ll,M' &M' "k Filed: Feb. 1971 ttorney ughruc, 0 we 1on 71nn acpca {2HAppl. No.2 112,904 ABSTRACT Electric accumulator cell arranged in a cellbox, the 2? 136/134 136/] 361 933 positive and negative essentiallyplane electrode plates 1 S being joined together into separate groups ofelec- 1 0 can 3 trodes by means of plate straps and being furtherlowered into a liquid electrolyte and provided with current dischargingmeans for withdrawal of current to a con- [56] Reerences Cured sumer,said withdrawal taking place through at least UNITED STATES PATENTS twocurrent discharging means connected to the'correl,l06,7l9 8/l9l4 Lake..l36/134R sponding number of plate straps 'on' the electrode 1,259,1933/1918 Ahlgren 136/134 R plates 944,078 12/1909 Decker 136/l34 R2,658,937 ll/l953 Chapman 136/134 R 10 Claims, 12 Drawing Figures 78 l ll PATENTEDBET 2 3,762,958 SHEET 20F 4 ELECTRICAL ACCUMULA TOR CELL ORACCUMULATOR BATTERY The present invention relates to a new and improvedtype of accumulator cells or electrical accumulator batteries made up ofa number of accumulator cells consisting of cell boxes with positive andnegative, essentially plane electrode plates, which are joined togetherinto positive and negative groups of electrodes, respec tively, by meansof plate straps and immersed in a liquid electrolyte, and of currentdischarging means or terminal posts.

Known accumulator cells of this type have groups of electrodes in whichthe electrode plates in each group are connected to a single platestrap, from which one or two terminal posts extend up through the lid ofthe cell box or out through the wall of the cell box above theelectrolyte level. Placement of the plate strap for an electrode groupof one polarity diagonal to the plate strap for the other electrodegroup is also known.

For use of these batteries a fairly large discharge of current is oftenrequired during a limited period, during which the terminal voltage ofthe battery must not fall below a given level. A noticeable internalvoltage drop then takes place in relation to the terminal voltage of thecell owing to the electric resistance in the actual cell, both onaccount of conduction of the current from the various points in theelectrode plates, where the current is generated, up to the plate strapand on account of the connection between plate strap and terminal post,and finally owing to the resistance in the terminal post.

The object of the present invention is to diminish the electricresistance in conjunction with discharge of current from the electrodes,so improving the performance of the cell. Through the invention this iseffected through the fact that the current paths in the .cell aregreatly shortened, chiefly because the discharge of current from everyelectrode or group of electrodes takes place through at least twocurrent discharging means which are connected to the correspondingnumber of plate straps on the electrode or group of electrodes.

For further reduction of the resistance in the accumulator cell it ispossible according to the invention to let the current discharging meanstake the shortest straight path out through the cell wall, whether thisoccurs above or below the electrolyte level in the cell. But difficultsealing problems then arise both in acid batteries, owing to thecorrosive effect of the acid and to its tendency to creep, and to aneven greater extent in alkaline batteries owing the known tendency ofthe alkaline electrolyte to creep past all seals. We have now discoveredthat the problem can be solved by arranging that at least one of thecurrent discharging means passes with sealing effect throughtheside-wall of the cell box below the electrolyte level, in which case theends of the plate straps facing the box wall must be formed into aflange and between the flange and the box wall are placed, essentiallyconcentrically, two packings of plastic material and with differentdiameters of hole, and that a non-drying sealing agent which isresistant to the electrolyte in the box is placed in a space betweenthese packings, the flange and the box wall.

The packings between which the sealing agent is enclosed may be ofoptional section such as square, rectangular or triangular. A preferredform is an O-ring with circular section. O'rings of this kind indifferent sizes are standard commercial articles.

Non-drying sealing agents suited for the purpose are usually of organicorigin. In alkaline batteries, for example, one can advantageously usean agent with the trademark Opanol, which is a liquid resin formed as aliquid or semi-liquid polymerization production of isobutylene, havinggood electrical insulating properties and resistant to both acids andlyes and effectively prevents any risk of creep of the electrolyte.

In conventional accumulator cells the terminal posts extend considerablyoutside the lid of the cell or, as the case may be, the side-wall. Butit is. a general desire that the total volume of the cells should belimited as far as possible. Through the invention the terminal parts ofthe accumulator cells can be arranged to lie practically on a plane withthe outer wall of the cell box. This is achieved through the fact thatthe plate straps are attached to the wall of the cell box by fasteningsin the form of externally threaded bolts fitting a correspondinginternal thread in the plate strap, the bolts having at one end a flangeand an internal thread in which the current discharging means is fixed.This arrangement, as will be shown later, also makes the accumulatorcells easily extensible without the total volume of the accumulatorbattery thereby assuming unnecessarily large proportions.

This form of construction can be applied direct to cell boxes ofinsulating material. For cell boxes of electrically conductive material,insulators are placed on each side of the box wall at the bushing.

The design of the plate straps, referred to above, with a flange forsealing against the wall of the cell box, has other advantages as well.This flange can be used as support for fitting of the electrode platesto the plate strap. This is done according to a suitable embodiment byfurnishing the ends of the plate straps remote from the flange with anexternalor internal thread and by clamping the electrode plates withintermediate spacers between the flange and a nut or headed screwtightened in the thread. The invention is, however, not limited to thisattachment of the electrode plates to the plate strap. Within the scopeof the invention, use can also be made of plate straps to which theelectrode plates are fastened, for example, by welding, soldering orriveting.

According to another embodiment, in order to reduce the current paths inaccumulator cells with a large number of electrode plates, the number ofelectrode plates with the same polarity is divided into two groups andthe current discharge lugs are led out through op posing walls in thecell box. If the number of plates is not evenly divided between the twogroups, unbalanced loading of the cell may arise in operation. This mustal ways be the case if the total number of electrode plates with thesame polarity is odd. This is remedied according to the invention byinterconnecting the two groups of electrodes of the same polaritythrough an electrically conducting connecting device. This ensures anequalization of the load on the two groups. This connecting deviceshould preferably be of a flexible material such as a tape or a cable ofelectrically conducting material, so avoiding mechanical strains.

Several methods are known for coupling together a number of accumulatorcells into a battery. A usual method is to use a common cell box withpartition walls which separate the individual cells. The junctionbetween the cells is then usually effected through terminal posts,extending up through and a bit beyond the lid of the accumulator batteryand connecting bars or cables between the terminal posts of the variouscells. Bushings are also used between the various cells, which passthrough the partition walls in the battery box above the electrolytelevel. Connecting bars placed in sealed extensions of the sides of thebattery box have also been proposed. These batteries are all limited bythe number of cells the battery box is designed for. Often, however, itis desired to combine an arbitrary number of accumulator cells into abattery intended for a specific purpose, while keeping the total volumeof the battery as small as possible. The coupling together of separateaccumulator cells by connectors which snap into one another is alreadyknown. These connectors, however, provide poor electrical contact andpoor mechanical coupling of the various accumulator cells.

A rapidly and simply coupled accumulator battery of an arbitrary numberof accumulator cells according to this invention, and of very compresseddesign, is achieved by coupling together the accumulator cells withconnecting bars running along the outer sides of the cell box, theconnecting bars being clamped by means of the current discharging means.

One may also conceive of an alternative embodiment according to theinvention, with every current discharging means common to two adjacentcells and having the form of a bolt with external right-hand thread atone end and external left-hand thread at the other end and a washer withexternal key-grip fitting slidably but not rotatably on the bolt, andthe accumulator cells having the terminal devices for the currentdischarging means left-hand-threaded for electrode groups of a givenpolarity and right-hand-threaded for electrode groups of the oppositepolarity.

At the outer terminals of an accumulator battery according to theinvention all current discharge lugs of the same polarity may suitablybe interconnected with a common bar matching the external shape of thecell.

An example of the improvement of performance in a battery according tothe invention over a battery of cells of earlier known design is shownby discharge curves in FIGv 1. The curves were measured at discharge offully charged cells with rated capacity C 80 Ah. The discharge currentis X C, i.e., 400 A, and the temperature C. The curves show the cellvoltage in relation to discharge time. The dotted curve relates to astandard cell with a single plate strap per group of electrodes and withconventional terminal posts extending up through the lid of the cell.The fully drawn curve shows the result at discharge of a batteryaccording to the invention. Every group of electrodes has a plate strapat the upper part of the group of electrodes and one at the lower partof the group of electrodes. In both cases the current discharges takeplace through the nearest cell wall linearly to the respective platestrap. The battery consists of five cells connected in series with barsrunning along the outer sides of the cell boxes in the manner describedabove. The curve shows the average cell voltage during a discharge. Itwill be seen from the curves that the battery according to the inventionshows, on an average, a more than 10 percent higher cell voltage thanthe conventional cell.

Another example of improvement of performance is shown by the high-loadcharacteristic in FIG. 2. The curves were recorded with the same cellsas in the preceding example and relate to fully charged cells at atemperature of 21 C. The dotted curve shows the performance of thestandard cell and the fully drawn curve the performance of a batteryaccording to the invention. The curves show V/cell after a dischargetime of 1 second at varying discharge current. It will be seen from thecurves that the amperage withdrawable during 1 second at a voltage of,for example, 1 V and the said temperature is 45 percent greater in cellsaccording to the invention than in conventional cells. This type ofcurve is used for the design of batteries for operation of startermotors. For this purpose the battery must be able to deliver a givenhigh starting current without falling below a minimum voltage level. Itwill be realized that, for a given motor, it will suffice with a batteryof lower capacity according to the invention than otherwise, and in thisway a saving is obtained both in volume and weight since batteries withlower capacity have also a lower volume and weight.

Cells of design according to the invention become more compact thanconventional cells, which in itself brings a saving of volume andweight.

The invention is explained in the following drawings:

FIG. 1 shows comparative discharge curves that have already beendescribed.

FIG. 2 shows comparative high-load characteristics that have alreadybeen described.

FIG. 3 is a partially exposed perspective view of part of an accumulatorbattery according to the invention.

FIG. 4 shows a partially sectioned part of a plate strap with currentdischarging means and connecting bar in an accumulator battery with cellbox of insulating material according to the invention.

FIG. 5 shows the attachment of the plate strap in a cell box ofelectrically conductive material.

FIG. 6 shows the attachment of an alternative type of plate strap withwelded electrode plates.

FIG. 7 shows a fastening device for the electrode groups for use forextensible cells, designed for cell boxes of insulating material.

FIG. 8 shows the same device for cell boxes of electrically conductivematerial.

FIG. 9 is a partially sectioned side view of two accumulator cellscoupled together by an alternative method.

FIG. 10 shows an enlarged section of a coupling device for couplingaccording to FIG. 9.

FIG. 11 shows a detail ofa current discharging means according to FIGS.9 and 10.

FIG. 12 shows a side-view of a washer for the current discharging meansaccording to FIG. 11.

In FIG. 3 two accumulator cells 10 have cell boxes 12 of electricallyinsulating material. 14 is a group of electrodes of a given polarity,e.g., positive, and 16 is then a negative group of electrodes. Thecurrent is withdrawn from the groups of electrodes through currentdischarging means 18, which at the same time clamp the groups ofelectrodes 14, 16 to the inside of the wall of the cell box 12 and theconnecting bars 20 to the outside of the same wall (see also FIG. 4).One external terminal of the battery, which in this case is thepositive, consists of a bar 22, which matches the outer shape of thecell box 12, with a battery connecting piece 24, the bar being connectedby means of current discharging means 18 to all current discharge lugsfrom the positive group of electrodes in the accumulator cell.

In FIG. 4 a plate strap 26 has its end facing the wall of the box 12formed as a flange 28. In the flange is a cut-out 30 in which a packingin the form of an O-ring 32 of larger diameter and a packing in the formof an O-ring 34 of smaller diameter are essentially concentricallyplaced. The space 36 between the O-rings 32, 34 and the flange 28 andthe wall of the box 12 is filled with a non-drying sealing agent, e.g.,a liquid resin, which is available commercially under the tradenameOpanol," which is a liquid or semi-liquid polymerization product ofisobutylene having good electrical insulating properties and resistantto both acids and lyes. The end of the plate strap 26 remote from theflange has an external thread 38. Groups of electrodes 40 and spacers 42with holes or slots for the plate strap are fitted over the plate strap26 and clamped between the flange 28 and nut 44 to form a group ofelectrodes 14 or 16. Alternatively the end of the plate strap 26 canhave an internal thread and the electrode plates 40 with intermediatespacers 42 can be clamped to the flange 28 with a headed screw. At thesame end as the flange 28 the plate strap 26 has an internal thread 46into which the current discharging means 18 fits. The group ofelectrodes l4, l6 and the connecting bar are clamped by the currentdischarging means to the wall of the box 12 as already described. Aconnecting device 45 can be attached by its end to the group ofelectrodes 14 or 16, e.g., with the nut 44 or a headed screw inaccordance with the aforesaid alternative. This connecting device 45 ismade of an electrically conductive material and is preferably, thoughnot necessarily, flexible. Its other end is attached in the same orsimilar manner to another group of electrodes 14 or 16 of the samepolarity (not shown in the figure), which is clamped in the same way asshown in the figure, but to the opposite wall of the cell box.

In FIG. 5 the wall of the box 48 is made of an electrically conductivematerial, e.g., steel plate. A packing of insulating material 50 andwith larger diameter of hole than the outer diameter of the O-ring 32 isplaced between the wall of the box 48 and the flange 28. The packing 50may advantageously have a collar 52 which partially surrounds the outeredge of the flange 28. Another packing of insulating material 54 has anouter diameter which is less than the inner diameter of the O- ring 34.The packing has a collar 56 which extends through a hole in the wall ofthe box 48 and the inner diameter of which matches the outer diameter ofthe current discharging means 18. A packing 58 is placed between thewall of the box 48 and the connecting bar 20. This packing 58 canadvantageously have the same surface dimensions as the connecting bar 20and thus be common to two accumulator cells.

FIG. 6 shows an alternative type of plate strap 60 with an angularflange 62, which is thickened in the example shown. The electrode plates40 are fastened to the plate strap 60 in the known manner by means ofwelds 64. In the manner described with reference to FIG. 4 the flange 62has a cut-out 30 and an internal thread 46. The sealing and clamping tothe wall of the box 12 are achieved in the same way as described withreference to FIG. 4.

FIG. 7 shows a fastening device 66 with external thread 68 fitting intothe corresponding internal thread 70 in the plate strap 26. With itsexternally threaded portion 68 the fastening device 66 is threaded fromwithout through a hole in the wall of the box 12. On the outside of thewall of the box 12 the fastening device 66 has a flange 72 which isfurnished with some form of key-grip 74. In the example illustrated thekey-grip has the form of two holes. In order that the outer surface ofthe flange 72 shall come in the same plane as the outer surface of thewall of the box 12, the latter has a depression 76. The fastening device66 is furnished from the flange side with an internal thread 78 whichfits the thread of the current discharging means 18. The seal betweenthe plate strap 26 and the wall of the box 12 is achieved in the sameway as previously described with reference to FIG. 4.

FIG. 8 shows the same construction as FIG. 7, but at tached to a boxwall 48 of electrically conductive mate rial. Between the flange 28 andthe wall of the box 48 is placed a packing 50 of the same type asdescribed under FIG. 5. Between the flange 72 on the fastening device 66and the wall of the box 48 has been placed a packing 80 of electricallyinsulating material. In the example shown the packing 80 has a collar 82extending through the hole in the wall of the box 48 and an outer flange84 which partially surrounds the outer edge of the flange 72.

FIG. 9 shows two accumulator cells 10 with cell box 12, each having afilling valve 86. A positive group of electrodes 14 in one accumulatorcell is coupled to a negative group of electrodes 16 in the otheraccumulator cell. Each group of electrodes has two plate straps 26 withfastening device 66. The accumulator cells 10 are electrically andmechanically coupled together by current discharging means 88 which arescrewed down by means of the washers 90 with key-grip.

FIG. 10 shows a positive group of electrodes 14 and a negative group ofelectrodes 16 with plate straps 26 and fastening devices 66, one ofwhich has an internal right-hand thread 78 and the other an internalleft-hand thread 92. Into these threads is drawn a current dischargingmeans 88 by means of the washer 90 slidably but not rotatably placed onit. A good electrical contact is achieved via the two flanges 72 on thefastening devices 66 and the washer 90 made of electrically conductivematerial.

FIG. 11 shows a current discharging means 88 formed as a bolt with anexternal right-hand thread 96 and an external lefthand thread 98 and,between these threads, a part 100 which in the example shown has twomilled portions so as to follow the rotation of the washer 90 placedround the part 100. This washer 90, through two spot welds 106, iscomposed of two identical halves 94.

FIG. 12 shows a washer 90 composed of. two halves 94. Each half has aslot 102 running across the center of the washer and terminating in arounded portion 104. For mounting of the current discharging means 88 awasher 94 is passed over the milled part 100 from each side and the twohalves are joined together with two spot welds 106. On coupling togetherof two accumulator cells the cells will always be tightly drawn togetherirrespective of whether the left-hand and righthand threads gripsimultaneously and irrespective of any differences in tolerance whichmay exist between the various accumulator cells. In the example in thefigure the washer 90 is shown with a. key-grip in the form of a hexagon.Obviously any other kind of key-grip with which the washer can be turnedwith a tool serves the same purpose. Furthermore the slidability of thewasher on the current discharging means can be otherwise arranged. Forexample an axial slot can be milled in the current discharging means anda tap-screw screwed into it via a radially threaded hole in the washer.

What I claim is:

1. Electric accumulator cell or accumulator battery assembly in whicheach accumulator cell consists of a cell box, positive and negativeessentially plane electrode plates joined together into positive andnegative groups of electrodes by means of plate straps, a liquidelectrolyte, and current discharging means for withdrawal of currentfrom said electric accumulator battery, characterized in that thecurrent withdrawal from the respective electrode plates or electrodegroups (14, 16) takes place through at least two current dischargingmeans (18) connected to the corresponding number of plate straps (26) onthe electrode plates or electrode groups, at least one of the positiveor negative current discharging means (18) extending in sealingrelationship perpendicularly through the side-wall of the cell box (12)below the electrolyte level the ends of the plate straps (26) facing thewall of the box (12) being formed as a flange (28), between which flange(28) and the wall of the box (12) are placed, essentially concentricallywith said flange, two packing (32, 34) of plastic material and havingdifferent diameter holes therethrough to form a space therebetween, insaid space (36) between said packings, said flange and the wall of thebox is contained a non-drying sealing agent which is resistant to theelectrolyte in the box (12).

2. Electric accumulator cell according to claim 1, characterized in thatthe two packings (32, 34) of plas tic material have the form of O-rings.

3. Electric accumulator cell according to claim 1, characterized in thatthe non-drying sealing agent consists of a liquid resin.

4. Electric accumulator cell according to claim 1, characterized in thatthe plate straps (26) are attached to the wall of the cell box (12) bymeans of fastening device (66) formed as externally threaded (68) boltsfitting into a corresponding internal thread in each plate strap (26),the bolts having at one end a flange (72) and an internal thread intowhich the respective current discharging means (18) are fastened.

5. Electric accumulator cell according to claim 1, characterized in thatinsulating washers (54, 58) are placed on each side of the wall of thebox (48) at the passage of the current discharging means through theside-wall of the cell box.

6. Electric accumulator cell according to claim 1, characterized in thatthe ends of the plate straps remote from the flange have an external(38) or internal thread and that electrode plates with intermediatespacers (42) are clamped between the flange (28) and a nut (44) orheaded screw tightened in the thread.

7. Electric accumulator cell according to claim 1, characterized in thatthe number of electrode plates of the same polarity is divided into twogroups and that the current discharge lugs (18) are led out through twoopposing walls in the cell box (12).

8. Electric accumulator cell according to claim 7, characterized in thatthe two groups of electrodes of the same polarity are joined together byan electrically conductive connecting device (45).

9. Electric accumulator battery composed of accumulator cells accordingto claim 4, characterized in that each current discharging means (88) iscommon to two adjacent cells (10) and has the form of a bolt withexternal right-hand thread (96) at one end and external left-hand thread(98) at the other end and a washer (90) with external key-grip slidablybut not rotatably placed on the bolt.

10. Electric accumulator battery composed of accumulator cells accordingto claim 4, characterized in that the accumulator cells (10) have thefastening devices (66) for the current discharging meansleft-handthreaded (92) for a group of electrodes of a given polarity andright-hand-threaded (78) for a group of electrodes of opposing polarity.

v UNITED STATES PATENT oTTTcE CERTIFICATE OF CORECTION Patent No. 3,762, 958 Dated October 2, 1973 Inventofls) John Fredrik KUYLENSTIERNA Itcertified that error appears in the above-identifiedI patent and thatsaid Letters Patent are hereby corrected as shown below:

In the Heading:

The claim to priority was omitted. Please insert the following:

- Priority Data Sweden 1630/70 February 9, 1970- Signed and sealed this15th day of January 197A.

(SEAL) Attest:

EDWARD M. FLETCHER, JR. RENE D. TEGTMEYER Attesting Officer ActingCommissioner of Patents FORM PQ-IOSO (10-69) U.$. GOVERNMENT PRINTINGOFFICE: I959 0-366-33l,

2. Electric accumulator cell according to claim 1, characterized in thatthe two packings (32, 34) of plastic material have the form of O-rings.3. Electric accumulator cell accorDing to claim 1, characterized in thatthe non-drying sealing agent consists of a liquid resin.
 4. Electricaccumulator cell according to claim 1, characterized in that the platestraps (26) are attached to the wall of the cell box (12) by means offastening device (66) formed as externally threaded (68) bolts fittinginto a corresponding internal thread (70) in each plate strap (26), thebolts having at one end a flange (72) and an internal thread into whichthe respective current discharging means (18) are fastened.
 5. Electricaccumulator cell according to claim 1, characterized in that insulatingwashers (54, 58) are placed on each side of the wall of the box (48) atthe passage of the current discharging means through the side-wall ofthe cell box.
 6. Electric accumulator cell according to claim 1,characterized in that the ends of the plate straps remote from theflange have an external (38) or internal thread and that electrodeplates with intermediate spacers (42) are clamped between the flange(28) and a nut (44) or headed screw tightened in the thread.
 7. Electricaccumulator cell according to claim 1, characterized in that the numberof electrode plates of the same polarity is divided into two groups andthat the current discharge lugs (18) are led out through two opposingwalls in the cell box (12).
 8. Electric accumulator cell according toclaim 7, characterized in that the two groups of electrodes of the samepolarity are joined together by an electrically conductive connectingdevice (45).
 9. Electric accumulator battery composed of accumulatorcells according to claim 4, characterized in that each currentdischarging means (88) is common to two adjacent cells (10) and has theform of a bolt with external right-hand thread (96) at one end andexternal left-hand thread (98) at the other end and a washer (90) withexternal key-grip slidably but not rotatably placed on the bolt. 10.Electric accumulator battery composed of accumulator cells according toclaim 4, characterized in that the accumulator cells (10) have thefastening devices (66) for the current discharging meansleft-hand-threaded (92) for a group of electrodes of a given polarityand right-hand-threaded (78) for a group of electrodes of opposingpolarity.